Packet Core and Service Continuity Flashcards

What does the Ericsson 'Packet Core' solution need to support 'Roaming' between different operators?

Answer: Interconnect agreements and standard interfaces (S8 in LTE, N9 in 5G) via an IPX provider

Roaming in LTE uses the S8 interface (SGW to vPGW) and in 5G uses N9 (home UPF to visited UPF), traversing the IPX (IP eXchange) network under bilateral roaming agreements.

What is the 'Dedicated Bearer' concept in Ericsson's LTE EPC?

Answer: An additional EPS bearer created to give specific traffic flows different QoS from the default bearer

A Dedicated Bearer supplements the Default Bearer to provide specific QoS treatment (e.g., guaranteed bitrate for VoLTE) to particular traffic flows identified by TFT (Traffic Flow Template).

What does QCI (QoS Class Identifier) define in Ericsson's LTE EPC?

Answer: A standardized index mapping to specific packet forwarding characteristics (latency, loss, priority) for a bearer

QCI values (1–9 standardized, 65–70 for mission-critical) define the target packet delay budget, error loss rate, and scheduling priority for EPS bearers.

In Ericsson's 5G architecture, what does the N4 interface connect?

Answer: The SMF to the UPF, carrying PFCP session establishment and packet forwarding rules

The N4 interface uses PFCP (Packet Forwarding Control Protocol) to allow the SMF to program packet detection, forwarding, and reporting rules into the UPF.

What is Ericsson's 'Subscriber Data Management (SDM)' solution used for?

Answer: Centralizing subscriber profile storage and providing unified access for HSS, HLR, and AAA functions across network generations

Ericsson's SDM consolidates subscriber identity and profile data across 2G/3G/4G/5G, acting as a unified backend for HLR, HSS, UDM, and AAA nodes.

What does 'UE IP Address Preservation' during handover mean in Ericsson's packet core design?

Answer: The UE retains its IP address throughout mobility events so active sessions are not disrupted

Because the PGW/UPF acts as the IP anchor, the UE keeps the same IP address as it moves between eNBs or gNBs, preserving TCP/UDP sessions during handover.